text: /*
   * Copyright (C) 2015-2016 Open Source Robotics Foundation
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   *
  */
  #ifndef GAZEBO_SENSORS_IMUSENSOR_PRIVATE_HH_
  #define GAZEBO_SENSORS_IMUSENSOR_PRIVATE_HH_
  
  #include <array>
  #include <mutex>
  #include <ignition/math/Vector3.hh>
  #include <ignition/math/Pose3.hh>
  
  #include "gazebo/physics/PhysicsTypes.hh"
  #include "gazebo/transport/TransportTypes.hh"
  
  namespace gazebo
  {
    namespace sensors
    {
      /// \internal
      /// \brief Imu sensor private data.
      class ImuSensorPrivate
      {
        /// \brief transform from world frame to Imu reference frame.
        public: ignition::math::Quaterniond worldToReference;
  
        /// \brief Save previous imu linear velocity in the specified frame
        /// for computing acceleration in the specified frame.
        /// \sa worldToReference
        public: ignition::math::Vector3d lastImuWorldLinearVel;
  
        /// \brief Noise free linear acceleration
        public: ignition::math::Vector3d linearAcc;
  
        /// \brief store gravity vector to be added to the imu output.
        public: ignition::math::Vector3d gravity;
  
        /// \brief Imu data publisher
        public: transport::PublisherPtr pub;
  
        /// \brief Subscriber to link data published by parent entity
        public: transport::SubscriberPtr linkDataSub;
  
        /// \brief Parent entity which the IMU is attached to
        public: physics::LinkPtr parentEntity;
  
        /// \brief Imu message
        public: msgs::IMU imuMsg;
  
        /// \brief Mutex to protect reads and writes.
        public: mutable std::mutex mutex;
  
        /// \brief Buffer for storing link data
        public: std::array<boost::shared_ptr<msgs::LinkData const>, 2>
                incomingLinkData;
  
        /// \brief Index for accessing element in the link data array
        public: unsigned int dataIndex;
  
        /// \brief True if new link data is received
        public: bool dataDirty;
  
        /// \brief Noise free angular velocity.
        public: ignition::math::Vector3d angularVel;
      };
    }
  }
  #endif
  